Analysis of bull (Bos taurus) seminal vesicle fluid proteome in relation to seminal plasma proteome

Decoding the influence of semen collection processes on goat sperm quality from a perspective of seminal plasma proteomics

This study aims to assess the impact of semen collection methods on goat semen quality and seminal plasma (SP) proteomes. Semen was collected by artificial vagina (AV) or electro-ejaculator (EE) and semen parameters were evaluated. Tandem mass tag coupled with liquid chromatography-tandem mass spectrometry was used to screen SP differentially abundant proteins (DAPs) between EE and AV. PRM was used to confirm the reliability of the data. In contrast to EE, a lower volume, higher progressive motility and concentration were observed in AV. No differences were found in total motility, membrane integrity, acrosome integrity, and ROS production between EE and AV. In total, 1692 proteins were identified in SP, including 210 DAPs. Among them, 120 and 90 proteins were down-regulated and up-regulated in AV compared to EE, respectively. The GO annotation showed that DAPs are mainly localized in the membrane, involved in deference responses to bacterium, RNA processing, and related to oxidoreductase activity. KEGG demonstrated tight associations of DAPs with specific amino acids, carbon metabolism, citrate cycle, and propanoate metabolism. In conclusion, this study provides valuable insights into the effects of semen collection on goat semen quality and explores the potential action mechanism based on the modification of SP proteomes. SIGNIFICANCE OF THE STUDY: The quality of fresh semen directly influences the results of artificial insemination and semen cryopreservation in livestock. This study represents the first attempt to evaluate the impact of semen collection methods including electroejaculation and artificial vagina on sperm quality and seminal plasma proteomes in goat. The results of this study demonstrated that semen collection methods directly impacted the quality of goat semen. Then, the proteomic strategy was used to explore the potential action mechanism of semen collection methods on sperm. Some differentially abundant proteins that potentially influence semen quality were identified. Furthermore, this study suggests the possibility of utilizing specific proteins as predictive markers for goat semen quality.

Proteomic analysis of boar seminal plasma: Putative markers for fertility based on capacity of semen preservation at 17°C

Boar seminal plasma (SP) proteins were associated with differences on sperm resistance to cooling at 17°C. However, information about seminal plasma proteins in boars classified by capacity of semen preservation and in vivo fertility remains lacking. Thus, the objective was to evaluate the SP proteome in boars classified by capacity of semen preservation and putative biomarkers for fertility. The ejaculates from high-preservation (HP) showed higher progressive motility during all 5 days than the low-preservation (LP) boars. There was no difference for farrowing rate between ejaculates from LP (89.7%) and HP boars (88.4%). The LP boars presented lower total piglets born (14.0 ± 0.2) than HP (14.8 ± 0.2; p < 0.01). A total of 257 proteins were identified, where 184 were present in both classes of boar, and 41 and 32 were identified only in LP and HP boars, respectively. Nine proteins were differently expressed: five were more abundant in HP (SPMI, ZPBP1, FN1, HPX, and C3) and four in LP boars (B2M, COL1A1, NKX3-2, and MPZL1). The HP boars had an increased abundance of SP proteins related to sperm resistance and fecundation process which explains the better TPB. LP boars had a higher abundance of SP proteins associated with impaired spermatogenesis.

Proteomic analysis of high and low-motility frozen-thawed spermatozoa in yak provides important insights into the molecular mechanisms underlying sperm cryodamage

Sperm cryodamage caused by cryopreservation limits the use of frozen yak spermatozoa in artificial insemination (AI). However, the proteomic changes involved in the cryodamage of yak spermatozoa have not been investigated to date. Therefore, this study aimed to identify proteins related to freezing tolerance. Tandem mass tag (TMT) were used in combination with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for identifying differentially expressed proteins (DEPs) between high-motility (HM) and low-motility (LM) frozen-thawed yak spermatozoa. A total of 116 DEPs were identified (>1.5-fold, P < 0.05); of which, 104 proteins were upregulated in HM spermatozoa and 12 proteins were upregulated in LM spermatozoa. The results of functional annotation analysis revealed that the DEPs were mainly involved in metabolic processes. A total of 20 DEPs that were abundantly expressed in HM spermatozoa were strongly associated with carbohydrate metabolism. The results of KEGG analysis revealed that the DEPs were enriched in glycolysis/gluconeogenesis, PPAR signaling pathway, and Ras signaling pathway. In addition, many antioxidant enzymes such as superoxide dismutase (SOD1), peroxiredoxin-6 (PRDX6), and Parkinson disease protein 7 (PARK7) were upregulated in HM spermatozoa, suggesting that these enzymes affect the motility of spermatozoa by regulating the levels of reactive oxygen species (ROS) in frozen-thawed spermatozoa. Altogether, the findings of this study elucidate the mechanisms through which cryopreservation affects the movement of yak spermatozoa and offer a novel basis for refining freezing techniques and modifying cryopreservation extender components.

QTLs and Candidate Genes Associated with Semen Traits in Merino Sheep

Ram semen traits play a significant role in conception outcomes, which in turn may influence reproductive efficiency and the overall productivity and profitability of sheep enterprises. Since hundreds of ewes may be inseminated from a single ejaculate, it is important to evaluate semen quality prior to use in sheep breeding programs. Given that semen traits have been found to be heritable, genetic variation likely contributes to the variability observed in these traits. Identifying such genetic variants could provide novel insights into the molecular mechanisms underlying variability in semen traits. Therefore, this study aimed to identify quantitative trait loci (QTLs) associated with semen traits in Merino sheep. A genome-wide association study (GWAS) was undertaken using 4506 semen collection records from 246 Merino rams collected between January 2002 and May 2021. The R package RepeatABEL was used to perform a GWAS for semen volume, gross motility, concentration, and percent post-thaw motility. A total of 35 QTLs, located on 16 Ovis aries autosomes (OARs), were significantly associated with either of the four semen traits in this study. A total of 89, 95, 33, and 73 candidate genes were identified, via modified Bonferroni, within the QTLs significantly associated with volume, gross motility, concentration, and percent post-thaw motility, respectively. Among the candidate genes identified, SORD, SH2B1, and NT5E have been previously described to significantly influence spermatogenesis, spermatozoal motility, and high percent post-thaw motility, respectively. Several candidate genes identified could potentially influence ram semen traits based on existing evidence in the literature. As such, validation of these putative candidates may offer the potential to develop future strategies to improve sheep reproductive efficiency. Furthermore, Merino ram semen traits are lowly heritable (0.071-0.139), and thus may be improved by selective breeding.

Candidate genes and proteins regulating bull semen quality: a review

Poor semen profile reflected by suboptimum fertility statistics is a concern in bulls reared for breeding purpose. A critical review of research on candidate genes and proteins associated with semen quality traits will be useful to understand the progress of molecular marker development for bull semen quality traits. Here, we have tabulated and classified candidate genes and proteins associated with bull semen quality based on a literature survey. A total of 175 candidate genes are associated with semen quality traits in various breeds of cattle. Several studies using candidate gene approach have identified 26 genes carrying a total of 44 single nucleotide polymorphisms. Furthermore, nine genome-wide association studies (GWASes) have identified 150 candidate genes using bovine single nucleotide polymorphisms (SNP) chips. Three genes, namely membrane-associated ring-CH-type finger 1 (MARCH1), platelet-derived growth factor receptor beta, and phosphodiesterase type 1, were identified commonly in two GWASes, which, especially MARCH1, are required to explore their regulatory roles in bull semen quality in in-depth studies. With the advancement of high-throughput-omic technologies, more candidate genes associated with bull semen quality may be identified in the future. Therefore, the functional significance of candidate genes and proteins need to be delved further into future investigations to augment bull semen quality.

Review: The role of male reproductive tract secretions in ruminant fertility

Male fertility largely depends on the ability to produce sperm that can transmit the paternal information onto the next generation. However, the factors that are critical for sperm function and the subsequent development of healthy offspring are still not completely understood in ruminants. Importantly, sperm function is not completely encoded by germ cell DNA, but rather, depends on sequential acquisition, loss, and modification of elements through interaction with secretions from the testes, epididymides, and accessory glands (collectively termed seminal plasma). In addition, these secretions can play a role in the inheritance of paternal environmental effects by progeny. This is likely achieved directly, by the regulation of sperm epigenetic effectors, and indirectly, by altering the female environment in which the individual develops. This review will provide an overview of the different organs that contribute to seminal plasma in ruminants, and summarise how their secretions shape sperm function and modulate the female reproductive tract. Finally, some consideration will be given to the potential of paternal factors to affect embryo development and offspring health in ruminants.

Transcriptomic analysis of the seminal vesicle response to the reproductive toxicant acrylamide

BACKGROUND

The seminal vesicles synthesise bioactive factors that support gamete function, modulate the female reproductive tract to promote implantation, and influence developmental programming of offspring phenotype. Despite the significance of the seminal vesicles in reproduction, their biology remains poorly defined. Here, to advance understanding of seminal vesicle biology, we analyse the mouse seminal vesicle transcriptome under normal physiological conditions and in response to acute exposure to the reproductive toxicant acrylamide. Mice were administered acrylamide (25 mg/kg bw/day) or vehicle control daily for five consecutive days prior to collecting seminal vesicle tissue 72 h following the final injection.

RESULTS

A total of 15,304 genes were identified in the seminal vesicles with those encoding secreted proteins amongst the most abundant. In addition to reproductive hormone pathways, functional annotation of the seminal vesicle transcriptome identified cell proliferation, protein synthesis, and cellular death and survival pathways as prominent biological processes. Administration of acrylamide elicited 70 differentially regulated (fold-change ≥1.5 or ≤ 0.67) genes, several of which were orthogonally validated using quantitative PCR. Pathways that initiate gene and protein synthesis to promote cellular survival were prominent amongst the dysregulated pathways. Inflammation was also a key transcriptomic response to acrylamide, with the cytokine, Colony stimulating factor 2 (Csf2) identified as a top-ranked upstream driver and inflammatory mediator associated with recovery of homeostasis. Early growth response (Egr1), C-C motif chemokine ligand 8 (Ccl8), and Collagen, type V, alpha 1 (Col5a1) were also identified amongst the dysregulated genes. Additionally, acrylamide treatment led to subtle changes in the expression of genes that encode proteins secreted by the seminal vesicle, including the complement regulator, Complement factor b (Cfb).

CONCLUSIONS

These data add to emerging evidence demonstrating that the seminal vesicles, like other male reproductive tract tissues, are sensitive to environmental insults, and respond in a manner with potential to exert impact on fetal development and later offspring health.

Seminal plasma insulin-like growth factor I and total protein concentration in peripubertal period of the Gyr bulls

This study aimed to evaluate the correlation of seminal plasma IGF-I and total proteins from peripubertal bulls with semen characteristics and onset of puberty. Sixteen dairy Gyr bulls were separated into early (n = 8) and regular (n = 8) groups, according to the onset of puberty. Semen was monthly collected by electroejaculation from 14 to 26 months of age, and the onset of puberty was retrospectively determined (17.0 ± 1.6 and 19.2 ± 1.5 months, to early and regular group, respectively). Five time points were evaluated (day -60, day -30, day 0, day 30 and day 60 days of puberty), being day 0 considered as beginning of puberty. Scrotal circumference and body weight were also assessed. Semen characteristics were evaluated, the seminal plasma was separated by centrifugation and total protein and IGF-I concentrations were determined. There was no difference between groups to concentration of the seminal plasma total proteins, but we found an interaction between group and age. Seminal plasma IGF-I concentrations were not different between early and regular groups; thus, the data were combined for analysis. Combined IGF-I concentrations were positively correlated with sperm motility and concentration, age, body weight and scrotal circumference. Negative correlation was found between IGF-I concentration and total sperm defects. Increased IGF-I was observed in day -30 and day 0 of puberty in early and regular groups, respectively. Seminal plasma total proteins are involved in peripubertal modifications and IGF-I from Zebus dairy bulls can influence the seminal characteristics and the growth factor increase occurs concomitantly with body growth but cannot be used to define puberty bulls earlier.

Comparative Proteomic Analysis of Young and Adult Bull (Bos taurus) Cryopreserved Semen

The age of the bull is widely accepted to influence the production of sperm, affecting the amount and quality of produced semen, which in turn impacts the results of cryopreservation. However, the exact influence of the maturation process on cryopreserved sperm, as well as the underlying molecular mechanisms of this process, are not fully understood. The goal of this study was to evaluate changes in the proteome of thawed semen (spermatozoa and supernatant) collected from young and adult bulls (n = 6) using the 2D-DIGE approach. The quality of semen was assessed using a CASA system and flow cytometry. We found no significant age-related variation in semen quality, with the exception of the average path velocity of sperm movement, which was higher in adult bulls. Proteomic analysis indicated 15 spermatozoa proteins and 10 supernatant proteins with significant age-related changes. Our results suggest that semen from adult bulls is better equipped with proteins related to energy production, protection of spermatozoa against oxidative stress and fertilizing ability. Proteins increased in abundance in young bull spermatozoa were connected to the cytoskeleton and its development, which strongly suggests that developmental processes are still in progress. In conclusion, our results provide novel insight into the mechanism of the development of the male reproductive system of cattle.

Aldose Reductase B1 in Pig Seminal Plasma: Identification, Localization in Reproductive Tissues, and Relationship With Quality and Sperm Preservation

Aldose reductase B1 (AKR1B1), a NADPH-dependent enzyme that belongs to the aldo-keto reductase protein superfamily, has been reported to be involved in both male and female reproductive physiology. The objectives of this study were: (1) to evaluate the concentration of SP-AKR1B1 in pig ejaculate fractions; (2) to describe the immunohistochemical localization of AKR1B1 alongside the boar genital tract; (3) to evaluate the relationship between SP-AKR1B1 and sperm quality/functionality parameters. Ejaculates from seven boars (one ejaculate per boar) were collected in separate portions [the first 10 mL of the sperm rich fraction (SRF-P1), the rest of the SRF (SRF-P2), and the post-SRF (PSRF)], and the concentration of SP-AKR1B1 was assessed using an enzyme-linked immunosorbent assay (ELISA). Immunohistochemistry and immunoblotting targeting was conducted in the reproductive tissues of these boars. Additionally, the entire ejaculates of 14 boars (one ejaculate per boar) were collected and split into three separate aliquots for: (i) SP-AKR1B1 quantification; (ii) assessment of sperm concentration and morphology; and (iii) evaluation of sperm quality and functionality parameters upon ejaculate collection (0 h) and after 72 h of liquid storage at 17°C. Concentration of AKR1B1 in the SP of SRF-P1 (458.2 ± 116.33 ng/mL) was lower (P < 0.05) than that of SRF-P2 (1105.0 ± 229.80 ng/mL) and PSRF (1342.4 ± 260.18 ng/mL). Monomeric and dimeric AKR1B1 forms were expressed alongside the reproductive tissues, except in the bulbourethral glands. No relationship between SP-AKR1B1 and sperm quality/functionality parameters was observed either at 0 h or after 72 h of storage at 17°C. In conclusion, AKR1B1 is expressed in the reproductive organs of boars (except bulbourethral glands) and a higher concentration is found in the PSRF suggesting that seminal vesicles would be the main secretory source. However, this enzyme does not appear to be related to sperm quality/functionality or to the sperm ability to withstand liquid storage at 17°C.

Seminal Plasma: Relevant for Fertility?

Seminal plasma (SP), the non-cellular component of semen, is a heterogeneous composite fluid built by secretions of the testis, the epididymis and the accessory sexual glands. Its composition, despite species-specific anatomical peculiarities, consistently contains inorganic ions, specific hormones, proteins and peptides, including cytokines and enzymes, cholesterol, DNA and RNA-the latter often protected within epididymis- or prostate-derived extracellular vesicles. It is beyond question that the SP participates in diverse aspects of sperm function pre-fertilization events. The SP also interacts with the various compartments of the tubular genital tract, triggering changes in gene function that prepares for an eventual successful pregnancy; thus, it ultimately modulates fertility. Despite these concepts, it is imperative to remember that SP-free spermatozoa (epididymal or washed ejaculated) are still fertile, so this review shall focus on the differences between the in vivo roles of the SP following semen deposition in the female and those regarding additions of SP on spermatozoa handled for artificial reproduction, including cryopreservation, from artificial insemination to in vitro fertilization. This review attempts, including our own results on model animal species, to critically summarize the current knowledge of the reproductive roles played by SP components, particularly in our own species, which is increasingly affected by infertility. The ultimate goal is to reconcile the delicate balance between the SP molecular concentration and their concerted effects after temporal exposure in vivo. We aim to appraise the functions of the SP components, their relevance as diagnostic biomarkers and their value as eventual additives to refine reproductive strategies, including biotechnologies, in livestock models and humans.

Seasonal differences in seminal plasma proteins from two bovine breeds adapted to a subtropical climate

This study was designed to evaluate the seasonal expression of seminal plasma proteins from two bovine breeds adapted to a subtropical climate and their associations with post-thawing sperm and environmental characteristics. Semen samples were obtained three times in summer and three times in winter from four Crioulo Lageano and four Angus bulls. Seminal plasma was obtained by centrifugation, and the other portion of the semen was cryopreserved. Seminal plasma proteins were identified by 2D-nanoUPLC-MS^E. Post-thawing assessments of sperm kinetics, morphology and membrane integrity were performed. Environmental data such as air temperature, air humidity and black globe temperature (BGT) were recorded, and the temperature-humidity index (THI) was calculated in summer and winter. Results showed that the climate varied significantly between seasons. Although no statistical differences were observed in semen quality between breeds, the protein profiles varied within and between seasons. We suggest that the most critical proteins in summer affecting sperm characteristics were TIMP-2, DNase, Clusterin, CFAH and GPx6. TIMP-2 and DNase showed a higher abundance in Crioulo Lageano in comparison with Angus, while Clusterin, CFAH and GPx6 presented a lower abundance. To the best of our knowledge, this is the first report of a recently evolved type of glutathione peroxidase, GPx6, in seminal plasma of bovines. In winter, five proteins were considered to be more critical: BSP1, BSP3, CCL2, Sulfhydryl oxidase and TIMP-2. BSP1 and TIMP-2 showed a lower abundance while BSP3, CCL2 and Sulfhydryl oxidase presented a higher abundance in this season in Crioulo Lageano in comparison with Angus.

The Epigenetics of Gametes and Early Embryos and Potential Long-Range Consequences in Livestock Species-Filling in the Picture With Epigenomic Analyses

The epigenome is dynamic and forged by epigenetic mechanisms, such as DNA methylation, histone modifications, chromatin remodeling, and non-coding RNA species. Increasing lines of evidence support the concept that certain acquired traits are derived from environmental exposure during early embryonic and fetal development, i.e., fetal programming, and can even be "memorized" in the germline as epigenetic information and transmitted to future generations. Advances in technology are now driving the global profiling and precise editing of germline and embryonic epigenomes, thereby improving our understanding of epigenetic regulation and inheritance. These achievements open new avenues for the development of technologies or potential management interventions to counteract adverse conditions or improve performance in livestock species. In this article, we review the epigenetic analyses (DNA methylation, histone modification, chromatin remodeling, and non-coding RNAs) of germ cells and embryos in mammalian livestock species (cattle, sheep, goats, and pigs) and the epigenetic determinants of gamete and embryo viability. We also discuss the effects of parental environmental exposures on the epigenetics of gametes and the early embryo, and evidence for transgenerational inheritance in livestock.

Effect of Simmental bull seminal plasma protein in egg yolk-citrate extender on Kacang buck semen fertility

The genetic resources of Indonesia's indigenous Kacang goat require preservation. Artificial insemination is expected to accelerate population increases and preserve genetic resources simultaneously. The present study was the maiden attempt for cryopreservation of Kacang buck sperm. The objectives of this study were to determine whether the supplementation of superior Simmental bull seminal plasma protein in egg yolk-citrate extender could improve the quality of post-thawed Kacang buck sperm, increase conceptions rates, and improve kidding rates. Buck semen was diluted without supplementation (T0) and with supplementation of 2.5 mg (T1) and 5 mg (T2) of Simmental bull seminal plasma protein per mL egg yolk-citrate extender. Extended semen was packed in 0.25 mL straw as cryopreserved frozen semen. Post-thawed semen samples were evaluated for viability, motility, intact plasma membranes, malondialdehyde level, and DNA fragmentation. Estrus was synchronized for sixty Kacang does, which were divided randomly into three groups and inseminated using post-thawed semen. The progesterone serum concentration of the does was measured 7 and 22 days post-insemination to detect ovulation and conception. Pregnancy was confirmed using abdominal palpation at 43 days post-insemination and by observing birth. The T1 group showed the highest (P < 0.05) post-thawed viability, motility, and intact plasma membrane. Conception, pregnancy and kidding rates were also higher in T1 than other treatment groups. In conclusion, the 2.5 mg Simmental bull seminal plasma protein supplementation per mL egg yolk-citrate extender provided the best seminal quality and fertility of post-thawed Kacang buck semen.

The effect of false mount on quality of frozen-thawed semen in Bos indicus beef bulls

This study evaluated the effect of false mounts (FM) on quality of frozen-thawed semen in beef bulls. Five mature Brahman bulls at the Standard Semen Production Center in Thailand were subjected to semen collection. Overall, 60 ejaculates were collected over a 12-week period of which 30 were collected without, and another 30 were collected using FM. A range of quality parameters of fresh, pre-frozen, and frozen-thawed semen were evaluated. Use of FM resulted in significant improvement of most parameters of fresh semen except progressive motility and sperm viability. The quality parameters of pre-frozen and frozen-thawed semen also significantly improved with FM. Use of FM significantly improved the viability of frozen-thawed semen, possibly indicating the protective effect of seminal plasma proteins.

Effects of increased scrotal temperature on semen quality and seminal plasma proteins in Brahman bulls

Environmental temperature has effects on sperm quality with differences in susceptibility between cattle subspecies and breeds, but very little is known about the seminal plasma protein (SPP) changes resulting from testicular heat stress. Scrotal insulation (SI) for 48 hr was applied to Brahman (Bos indicus) bulls. Semen was collected at 3-day intervals from before, until 74 days post-SI. The changes in sperm morphology and motility following SI were comparable to previously reported and differences were detected in measures of sperm chromatin conformation as early as 8 days post-SI. New proteins spots, in the SPP two-dimensional (2-D) gels, were apparent when comparing pre-SI with 74 days post-SI, and SPP identified as associated with mechanisms of cellular repair and protection. Similar trends between 2-D gel and Sequential Window Acquisition of All Theoretical Mass Spectra (SWATH-MS) data was observed, with SWATH-MS able to quantify individual SPP that otherwise were not resolved on 2-D gel. The SPP assessment at peak sperm damage (21-24 days) showed a significant difference in 29 SPP (adjusted p < .05), and identified six proteins with change in abundance in the SI group. In conclusion both spermatozoa and SPP composition of bulls are susceptible to temperature change incurred by SI, and SPP markers for testicular heat insults may be detected.

Bioinformatics approaches for improving seminal plasma proteome analysis

Reproduction efficiency of male animals is one of the key factors influencing the sustainability of livestock. Mass spectrometry (MS) based proteomics has become an important tool for studying seminal plasma proteomes. In this review, we summarize bioinformatics analysis strategies for current proteomics approaches, for identifying novel biomarkers of reproductive robustness.

Genome-wide association study for age at puberty in young Nelore bulls

Selection for bulls that would reach puberty early reduces the generation interval and increases fertility and herd productivity. Despite its economic importance, there are few QTL associated with age at puberty described in the literature. In this study, a weighted single-step genome-wide association study was performed to detect genomic regions and putative candidate genes related to age at puberty in young Nelore bulls. Several protein-coding genes related to spermatogenesis functions were identified within the genomic regions that explain more than 0.5% of the additive genetic variance for age at puberty in Nelore bulls, such as ADAM11, BRCA1, CSNK2A, CREBBP, MEIOC, NDRG2, NECTIN3, PARP2, PARP9, PRSS21, RAD51C, RNASE4, SLX4, SPA17, TEX14, TIMP2 and TRIP13 gene. Enrichment analysis by DAVID also revealed several GO terms related to spermatogenesis such as DNA replication (GO:0006260), male meiosis I (GO:0007141), double-strand break repair (GO:0006302), base excision repair (GO:0006284), apoptotic process (GO:0006915), cell-cell adhesion (GO: 0098609) and focal adhesion (GO:0005925). The heritability for age at puberty shows that this trait can be improved based on traditional EBV selection. Adding genomic information to the system helps to elucidate genes and molecular mechanisms controlling the sexual precocity and could help to predict sexual precocity in Nelore bulls with greater accuracy at younger age, which would speed up the breeding programme for this breed.

Integrated analysis of mRNAs and long noncoding RNAs in the semen from Holstein bulls with high and low sperm motility

Sperm motility is the main index used to assess the quality of bull semen. It may also be used to evaluate the fertility potential of bulls. Protein-coding mRNA and long noncoding RNA (lncRNA) participate in the regulation of spermatogenesis. Here, we employed strand-specific RNA sequencing to profile the semen transcriptome (mRNA and lncRNA) of six paired full-sibling Holstein bulls with divergent sperm motility and to determine the functions of mRNA and lncRNA in sperm motility. Among 20,875 protein-encoding genes detected in semen, 19 were differentially expressed between the high sperm motility group (H: H1, H2, and H3) and low sperm motility group (L: L1, L2, and L3). Of the 11,561 lncRNAs identified in sperm, 2,517 were differentially expressed between the H and L groups. We found that TCONS_00041733 lncRNA targets the node gene EFNA1 (ephrin A1), involved in male reproductive physiology. Our study provides a global mRNA and lncRNA transcriptome of bull semen, as well as novel insights into the regulation of neighboring protein coding by lncRNAs and the influence of mRNAs on sperm motility.

Differences in sperm protein abundance and carbonylation level in bull ejaculates of low and high quality

In breeding and insemination centres, significant variation in bull ejaculate quality is often observed between individuals and also within the same individual. Low-quality semen does not qualify for cryopreservation and is rejected, generating economic loss. The mechanisms underlying the formation of low-quality ejaculates are poorly understood; therefore, the aim of the present study was to investigate the proteomic differences and oxidative modifications (measured as changes in protein carbonylation level) of bull ejaculates of low and high quality. Flow cytometry and computer-assisted sperm analysis were used to assess differences in viability, reactive oxygen species (ROS) level, and sperm motility. To analyse changes in protein abundance, two-dimensional difference gel electrophoresis (2D-DIGE) was performed. Western blotting in conjunction with two-dimensional electrophoresis (2D-oxyblot) was used to quantitate carbonylated sperm proteins. Proteins were identified using matrix-assisted laser desorption/ionisation time-of-flight/time-of-flight spectrometry. High quality ejaculates were characterised by higher sperm motility, viability, concentration, and a lower number of ROS-positive cells (ROS⁺). We found significant differences in the protein profile between high- and low-quality ejaculates, and identified 14 protein spots corresponding to 10 proteins with differences in abundance. The identified sperm proteins were mainly associated with energetic metabolism, capacitation, fertilisation, motility, and cellular detoxification. High-quality ejaculates were characterised by a high abundance of extracellular sperm surface proteins, likely due to more efficient secretion from accessory sex glands and/or epididymis, and a low abundance of intracellular proteins. Our results show that sperm proteins in low-quality ejaculates are characterised by a high carbonylation level. Moreover, we identified, for the first time, 14 protein spots corresponding to 12 proteins with differences in carbonylation level between low- and high-quality ejaculates. The carbonylated proteins were localised mainly in mitochondria or their immediate surroundings. Oxidative damage to proteins in low-quality semen may be associated with phosphorylation/dephosphorylation disturbances, mitochondrial dysfunction, and motility apparatus disorders. Our results contribute to research regarding the mechanism by which low- and high-quality ejaculates are formed and to the identification of sperm proteins that are particularly sensitive to oxidative damage.

Proteomic landscape of seminal plasma associated with dairy bull fertility

Male fertility is the ability of sperm to fertilize the egg and sustain embryo development. Several factors determine the fertilizing capacity of mammalian sperm, including those intrinsic to sperm and components of the seminal plasma. The present study analyzed the seminal fluid proteome of Bos taurus and potential associations between proteins and fertility scores. Mass spectrometry coupled with nano HPLC allowed the identification of 1,159 proteins in the dairy bull seminal plasma. There were 50 and 29 seminal proteins more abundant in high (HF) low fertility (LF) bulls, respectively. Based on multivariate analysis, C-type natriuretic peptide, TIMP-2, BSP5 and sulfhydryl oxidase indicated relationship with HF bulls. Clusterin, tissue factor pathway inhibitor 2, galectin-3-binding protein and 5′-nucleotidase were associated with LF bulls. Abundance of NAD(P)(+)-arginine ADP-ribosyltransferase, prosaposin and transmembrane protein 2 proteins had the highest positive correlations with fertility ranking. Quantities of vitamin D-binding protein, nucleotide exchange factor SIL1 and galectin-3-binding protein showed the highest negative correlations with fertility ranking. A fertility ranking score was calculated and the relationship with these proteins was significant (Spearman’s rho = 0.94). The present findings represent a major and novel contribution to the study of bovine seminal proteins. Indicators of fertility can be used to improve reproductive biotechnologies.

Metabolomic markers of fertility in bull seminal plasma

Metabolites play essential roles in biological systems, but detailed identities and significance of the seminal plasma metabolome related to bull fertility are still unknown. The objectives of this study were to determine the comprehensive metabolome of seminal plasma from Holstein bulls and to ascertain the potential of metabolites as biomarkers of bull fertility. The seminal plasma metabolome from 16 Holstein bulls with two fertility rates were determined by gas chromatography-mass spectrometry (GC-MS). Multivariate and univariate analyses of the data were performed, and the pathways associated with the seminal plasma metabolome were identified using bioinformatics approaches. Sixty-three metabolites were identified in the seminal plasma of all bulls. Fructose was the most abundant metabolite in the seminal fluid, followed for citric acid, lactic acid, urea and phosphoric acid. Androstenedione, 4-ketoglucose, D-xylofuranose, 2-oxoglutaric acid and erythronic acid represented the least predominant metabolites. Partial-Least Squares Discriminant Analysis (PLSDA) revealed a distinct separation between high and low fertility bulls. The metabolites with the greatest Variable Importance in Projection score (VIP > 2) were 2-oxoglutaric acid and fructose. Heat-map analysis, based on VIP score, and univariate analysis indicated that 2-oxoglutaric acid was less (P = 0.02); whereas fructose was greater (P = 0.02) in high fertility than in low fertility bulls. The current study is the first to describe the metabolome of bull seminal plasma using GC-MS and presented metabolites such as 2-oxoglutaric acid and fructose as potential biomarkers of bull fertility.

Identification and characterisation of the epididymal proteins in the lizard, Eutropis carinata (Reptilia, Squamata) (Schneider, 1801)

Lizards are seasonal breeders. Cyclic reproductive nature makes lizard as a useful model for the study of the reproductively active protein secretions in the epididymis. During breeding season, the epididymides of the lizard secret proteins that mixes with the spermatozoa and create a favourable environment for sperm maturation. In this spectrum, the aim of this study is to identify and characterize proteins which are present in the lumen of the epididymis of the lizard, E. carinata during the active phase of reproduction. The identification and analysis of the proteins are done through the proteomic approaches. The epididymal luminal fluid sample was taken from the reproductively active and inactive phase and these are subjected to the size exclusion chromatography. Two major peaks (peak 1 and peak 2) were obtained in the epididymal luminal fluid sample taken during the reproductively active phase. On the other hand, the sample from the reproductively inactive phase showed one peak (peak 1) whereas, peak 2 is not present during this phase. The peak 2 belong to reproductively active phase was later subjected to the proteomic analysis. Appropriate gel electrophoresis separation and purification methods are combined with LC-MS/MS in order to identify and characterize the proteins that are presented during the reproductively active phase. Further, in this work, nine proteins are identified including three enzymes and three heat shock proteins. Among the identified proteins, bioinformatics analysis predicts that majority of them are localized in the cytoplasm. In addition to this, an observation is made in the endoplasmic reticulum where it is seen that a close protein-protein interaction network of three molecular chaperones are involved in protein processing. Overall, this paper opens up a new dimension search for epididymal markers for the first time in reptiles, particularly lizards.